Atomic batteries, despite being called batteries, are not electrochemical and cannot be charged or recharged. And, compared to electrochemical batteries, atomic batteries have long lives and high energy density and are often used as power sources for equipment that is required to operate unattended for long periods of time. Unlike nuclear reactors, the batteries do not generate through a nuclear chain reaction.
Nuclear battery technology began in 1913, when Henry Moseley first demonstrated the beta cell. The field received considerable research attention for the possibility of a long-life power source for space exploration needs during the 1950s and 1960s. In 1954 RCA researched a small atomic battery for small receivers and hearing aids.
Since that time, many types and methods have been designed to extract electrical energy from nuclear sources. The scientific principles are well known, but modern nano-scale technology and new wide-bandgap semiconductors have created new devices and interesting material properties previously unavailable.
In 2009, Widetronix began working with Lockheed Martin to develop nuclear batteries for military applications. The batteries were expected to power electrical circuits that protect military planes and missiles from tampering, by destroying information stored in the systems or by sending out a warning signal to a military center. The batteries were also expected to last twenty five years. The battery was developed on the concept of betavoltaics and paired with benign isotopes such as tritium.
Researchers from the Moscow Institute of Physics and Technology (MIPT), the Technological Institute of Superhard and Novel Carbon Materials (TISNCM), and the National University of Science and Technology have optimized the design of a nuclear battery generating power from the beta decay of radioactive isotope nickel-63. The prototype packs about 3,300 milliwatt-hours of energy per gram, about ten times more than commercial chemical cells. The research team developed a way of increasing the power density of a nuclear battery almost tenfold. They developed and manufactured a betavoltaic battery using nickel-63 as the source of radiation and Schottky barrier-based diamond diodes for energy conversion.
Nano Diamond Battery (NDB) is developing a diamond nuclear-powered battery that is expected to last for up to 28,000 years. To build the nano diamond battery, NDB uses radioactive isotopes from nuclear waste with layers of paneled nano diamonds. The micro-sized single crystal diamonds rapidly move heat away from the radioactive isotope materials, and it is this transaction of thermal energy that generates electricity. The first prototype diamond nuclear voltaic battery concept using waste graphite from a graphite-cooled nuclear reactor was developed with heat-conducting diamonds pulling energy into electricity, a similar concept to NDB's, but with layers of the diamond and radioactive waste panels to generate higher amounts of energy. The challenge with these batteries is that the battery cell produces a small amount of energy and has to be combined in large numbers to power consumer devices.
Conversion techniques can be grouped into two types: thermal and non-thermal.
Thermal converters output power as a function of temperature differentials. Common types of thermal converters include thermoelectric and thermionic generators.
Thermal conversions
Non-thermal converters output power is not a function of temperature difference. They extract a fraction of the nuclear energy as it is being degraded into heat rather than using thermal energy to run electrons in a cycle.
Non-thermal conversions
Atomic batteries use radioisotopes that produce low energy beta particles or sometimes alpha particles of varying energies. Low energy beta particles are needed to prevent the production of high energy penetrating Bremsstrahlung radiation that would require heavy shielding. Radioisotopes that have been tested for use in atomic batteries include:
- Tritium
- Nickel-63
- Promethium-147
- Technetium-99
While radioisotopes that have been used in atomic batteries include:
- Plutonium-238
- Curium-242
- Curium-244
- Strontium-90